1. Field of the Invention
The present invention relates to a self-contained, transportable sewage treatment plant including clarifier and aerator chambers.
2. Description of the Prior Art
Self-contained, transportable, subterraneous sewage treatment apparatuses are commonly used in many rural communities. Typically, these apparatuses are constructed from concrete or fiberglass, cast as one part or formed from a number of parts. The apparatuses usually include a housing with panels which define internal aerator chambers and clarifier chambers.
The aerator chamber is the heart of the sewage treatment plant. Once the sewage is in the aerator chamber, it is oxygenated. Introduction of oxygen into the sewage intimately mixes the organics of the sewage with the bacteria populations in the aerator chamber, creating activated sludge. The bacteria reduce the organics of the sewage. Additionally, to maximize the oxygen content of the sewage, the sewage must circulate in a manner that maintains organic solids in suspension. If the organics are permitted to settle, they are less likely to be broken down by the bacteria.
Ideally, once the sewage has been treated sufficiently, when the bacteria has broken down a target amount of the organics in solution, the activated sludge passes from the aerator chamber into the clarifier chamber. In the clarifier chamber, any remaining solids in suspension which have not yet been broken down, settle, and are returned to the aerator chamber for continued circulation and breakdown. The treated waste water flows out of the clarifier chamber and is absorbed by the environment.
The key to consistent, efficient, and reliable sewage treatment is assuring that the proper amount of oxygen is introduced into the sewage for reaction with the bacteria. The speed at which reduction of the organics in the sewage is accomplished is directly related to the amount of oxygen that can be introduced into the sewage. The rate of oxygen introduction is directly related to the configuration of, and the diffusion means used to introduce oxygen in the aerator chamber. For this reason, proper configuration of the aerator chamber and the placement of the diffusers therein is crucial. One important way to enhance the oxygen content of the sewage is to increase the flow of the sewage within the chamber, perhaps even creating turbulent flow. A second way of enhancing the oxygen content is by maintaining oxygen at a high pressure in association with the sewage, similar to carbonating a beverage. The patent literature is replete with many sewage treatment apparatuses; however, none provide for enhancing sewage flow, nor associating gas at super-ambient pressure with sewage.
For example, U.S. Pat. No. 2,987,186, issued Jun. 6, 1961, to David W. Burgoon et al., describes an apparatus for treating waste materials. The apparatus includes a tank with a vertical wall that defines side-by-side aerating and clarifying chambers. A diffuser is centrally located in the aerating chamber for introducing oxygen therein. Activated sludge from the aerating chamber passes into the clarifying chamber via a through-bore located in the vertical wall. Particulate matter remaining in solution precipitates from solution and flows back into the aerating chamber via a conduit at the bottom of the vertical wall. The conduit has an outlet proximate to the diffuser. Presumably, the venturi effect of the oxygen being introduced into the aerator chamber draws the particulate matter back into the aerating chamber. The clarified sewage passes out of the clarifying chamber by an exit conduit and into the environment.
U.S. Pat. No. 3,195,727, issued Jul. 20, 1965, to Gary W. Kibbee, describes a waste products treatment apparatus having floating solid feedback structure. The device has laterally-disposed aerating and clarifying chambers. The clarifier chamber does not extend all the way to the bottom of the tank, rather an angled wall between the aerator chamber and the clarifier chamber projects into the outer wall of the clarifying chamber, above the bottom of the tank. A passageway exists between the angled wall and the outer wall, permitting particulate matter in suspension to return to the aerating chamber. The clarifier chamber also includes a baffle for trapping large particulate matter. On the other side of the baffle is a clarified liquid basin. Clarified sludge is voided from the clarified liquid basin into the environment.
U.S. Pat. No. 3,206,032, issued Sep. 14, 1965, to Mark C. Nottingham et al., describes a sewage disposal tank. The apparatus includes a tank, defining three, serial chambers. The first chamber, an aerator chamber, includes a number of diffusers which introduce oxygen into and circulate the sludge. Activated sludge from the aeration chamber passes into the second chamber after having passed through a baffle that filters out large particulate matter. The second chamber includes a centrally-and bottomly-disposed foraminous member for screening sewage introduced into the second chamber. Some of the screened sewage is returned to a pump and urged through the diffusers along with ambient air. The second chamber is in fluid communication with the third chamber by means of a weir located near the fluid surface of the sewage. This lighter, clarified sewage is conducted into the third chamber, a holding chamber for settling. The settled sewage is voided into the environment.
U.S. Pat. No. 3,805,957, issued Apr. 23, 1974, to Robert R. Oldham et al., describes a floating solids return device. The device includes a tank having three, serial chambers. The first chamber is a primary settling tank in which raw sewage is introduced and allowed to settle. The settling chamber is in communication with the secondary chamber, or aeration chamber, by means of a weir located near the surface of the sewage. The aeration chamber includes a diffuser which introduces oxygen into the sewage. Sewage from the aerator chamber passes into the clarifying chamber by means of another weir located proximate to the sewage surface. The clarifying chamber is defined by an angled outer wall and a vertical wall separating the clarifying chamber from the aerating chamber. The angled and vertical walls intersect above the bottom of the aerating chamber. The vertical wall has a passageway between the clarifying chamber and the aerating chamber permitting solid particulate matter to be returned into the aerating chamber. Treated sewage is voided from the clarifying chamber via yet another weir.
U.S. Pat. No. 3,951,817, issued Apr. 20, 1976, to John R. Snyder, describes a sewage treatment tank and tube settler. The device includes a diffuser located in the middle of and near the sewage surface of the aerating chamber. The device also is configured such that material from the aerating chamber passes through the lower passage between the aerating chamber and the clarifying chamber, rather than through the weir located at the water surface. The device includes a weir located at the surface between the aerating chamber and the clarifying chamber for conducting sewage from the clarifying chamber into the aerating chamber.
U.S. Pat. No. 4,859,325, issued Aug. 22, 1989, to Murphy Cormier, describes a waste material treatment apparatus. The apparatus includes a tank having two, serial chambers. The first chamber is an aerating chamber including a diffuser. Introduction of oxygen into the aerating chamber, along with the baffles in the chamber, induce a predetermined circulation of the sewage. The clarifying chamber receives sewage from the aeration chamber via a passageway between the vertical wall separating the two chambers and the angled wall defining the clarification chamber. Sewage from the clarification chamber passes into the environment via a weir located near the sewage surface in the clarification chamber.
U.S. Pat. No. 5,162,083, issued Nov. 10, 1992, to Lee W. Forbes et al., describes an individual home waste water treatment plant conversion apparatus. The apparatus includes a circular tank with diffusers circumferentially dispersed about the lower periphery of the tank. A clarifier insert depends centrally from the ceiling of the tank. The clarifier insert has a horizontal cross-sectional profile that is generally oval in shape. The insert is vertically tapered from top to bottom and has a lower aperture located at a predetermined distance above the bottom of the tank. The clarifier insert defines an internal clarifier chamber and two, vaguely-defined aerator chambers surrounding the insert. Sewage is introduced into the aerator chamber and circulated by the diffuser members. Oxygenated sewage passes from the aerator chamber into the clarifier chamber through the lower aperture of the insert member. Particulate matter remaining in solution settles on the inner surface of the insert member and returns to the aerator chamber. Fluid is voided from the clarifier chamber via a weir located near the sewage surface at the top of the clarifier chamber. Although the oval shape of the insert member essentially defines two aerating chambers, the definition is not as distinct, nor as effective as the configuration used in the present invention.
Clearly, the above demonstrates a need for a sewage treatment apparatus that includes structure for augmenting sewage flow, enhancing the oxygen content thereof. The above also demonstrates the need for a sewage treatment apparatus that associates oxygen at super-ambient pressure with sewage, also enhancing oxygenation.
None of the above inventions are seen as teaching or suggesting the presently claimed sewage treatment method or apparatus therefor.